Ocarina

Usosuki can play four notes on the ocarina, it is more or less the musical instrument of Yume Nisshi; similar to Madotsuki's flute, Urotsuki's trombone and Sabitsuki's headphones. There are numerous ways to reach this effect.

This is the easier way to get to the Ocarina effect. Enter the Red Sea via the Nexus and look for an island containing a tree with an egg in the branches. If the island is not reachable via blinking red dots to jump across, wake up and try again. Use the tree to access the Egg World, and enter a white egg in which there will be the effect.

The alternate route to the egg world involves going to the Bird's Eye Garden and into the grandfather clock. You'll end up in a sewer and you can go into the water with the Snow Bug effect. An entrance to a maze will be in the water, and you need to navigate it and look for a portal that looks like deer antlers. Follow the above instructions and you'll find the effect.

Enter the Mural World via the Nexus, find a pair of red neon pillars surrounded by red murals and go between them to be teleported to Orange Tiles Path. Follow it and interact with the NPC by the end of it, which will lead to the Red Bubbles Maze. Go east and you'll find another red NPC, interact with it and follow the path reaching the Egg World, then follow the instructions above.